WASHINGTON—Health and Human Services Secretary Sylvia Mathews Burwell said Thursday that a potential Supreme Court decision voiding the health law’s tax credits would create widespread disruption, but that federal officials were prepared to work with states to mitigate the effects.

A move by the court to strike a key component of the 2010 federal health-care overhaul could mean “the number of uninsured would jump dramatically” and that a “death spiral” would ensue in insurance markets in most of the country, she said, as sicker people kept coverage and healthier ones dropped it.

The federal government has provided tax credits to help low- and moderate-income consumers pay for health premiums in about three-dozen states through the HealthCare.gov website. The Supreme Court is set to rule later this month on whether the language of the Affordable Care Act restricts the credits to residents of the handful of states that opted to run their own insurance sites, officially called exchanges.

Secretary of Health and Human Services Sylvia Burwell said she was hopeful that more states will follow Indiana’s example and expand Medicaid. She spoke at a breakfast hosted by the Wall Street Journal Thursday.

“We believe we hold the right position,” Ms. Burwell said at a breakfast hosted by The Wall Street Journal. But “if that’s what the courts decide, we can’t undo the massive damage.”

The Republican Study Committee unveiled its blueprint for overhauling U.S. health-care if the Supreme Court cripples the federal health law in a decision expected later this month.

The official plan from the group of 170 House conservatives would repeal the entire 2010 Affordable Care Act starting Jan. 1, 2016. It would then replace the ACA’s centerpiece tax credits to help low and modest income people pay premiums and its requirements that insurers sell coverage to everyone regardless of their medical history with tax deductions and new insurance plans for people with pre-existing conditions.

Some Republicans, including 2008 presidential nominee Sen. John McCain, have long favored the idea, arguing it’s good tax policy, gives everyone the same choices, and doesn’t give people incentives to buy more expensive insurance.

A group of House conservatives on Thursday unveiled the latest version of their ObamaCare replacement plan — intentionally steering clear of a contentious court decision that could throw the law into flux.

The repackaged plan from the Republican Study Committee would fully repeal ObamaCare while creating new tax deductions and incentives for people to use health savings accounts.

It does not address Congress’s biggest debate over ObamaCare this year: how Republicans should respond to the looming case, King v. Burwell, if justices decide to strike down subsidies for 6.3 million people.

Millions of Americans could lose Obamacare subsidies under a Supreme Court ruling this month, but many in the GOP don’t need their votes anyway.

That’s a major political calculus for Tea Party Republicans, who are likely to resist any efforts to extend the subsidies, even temporarily. They’re much more worried about angering their base by appearing to concede to Obamacare than whether a handful of constituents lose their subsidies.

The American Action Forum recently assessed the plausible effects of a ruling for the plaintiff in the Supreme Court case, King v Burwell, concerning the legality of subsidies in the federally-run health insurance exchanges implemented under the Affordable Care Act. At the time of writing, the most up-to-date number for enrollees at risk of losing a health insurance subsidy was 7.7 million. But this week, the Center for Medicaid and Medicare Services released an update to enrollment figure that counts effectuated enrollment, which includes only households that have paid an insurance premium. As generally expected, roughly 15 percent of individuals with “plan selections” did not pay a premium and become actually enrolled. In light of this most recent update, roughly 6.6 million individuals across 37 states are at risk of losing their subsidies. The other impact estimates in the original AAF research remains unaffected, including 11.1 million people that will no longer face the threat of an individual mandate penalty.

The Supreme Court’s King v. Burwell ruling will make headlines whenever it arrives. It will also be genuine news to much of the country. The Kaiser Family Foundation’s Health Policy News Index, which tracks how closely the public follows health stories in the news, found that 59% of Americans have not been paying much or any attention to news stories about the case, and only 16% have been following very closely. That means that when the verdict comes the media’s first job will be to explain what the case was about.

The Affordable Care Act is once again before the Supreme Court. This time it’s not about whether the government can force you to have health insurance or pay a penalty. It can. That is so “2012.”

Now, in the case of King v. Burwell, the meaning of six words in a thousand-page law is under scrutiny. Those words could determine whether millions of Americans can afford to buy health insurance.

House conservatives are hinting at support for a temporary extension of Obama-Care subsidies if the Supreme Court cripples the law, even as they set up a working group to develop their own plan.

The high court is set to rule later this month in the case of King v. Burwell, which could invalidate subsidies for millions of people in at least 34 states using the federally run marketplace. Republicans say they need to be ready to address people losing their coverage, but have yet to coalesce around a plan.

Now another proposal is in the works. Members of the conservative House Freedom Caucus told The Hill they are setting up a group of four or five lawmakers, led by Rep. John Fleming (R-La.). The lawmakers will develop a plan meant to influence the main House working group led by Rep. Paul Ryan (R-Wis.) and two other panel chairmen, which Fleming complained is meeting in “secret.”

The Supreme Court could wipe away health insurance for millions of Americans when it resolves the latest fight over President Barack Obama’s health overhaul. But would the court take away a benefit from so many people? Should the justices even consider such consequences?

Several high-profile Republican governors are building pressure on Congress to come up with a plan if the Supreme Court decides to void subsidies for millions of people in their states.

Florida Gov. Rick Scott and Wisconsin Gov. Scott Walker both said Tuesday they are opposed to any kind of state-level fix to restore ObamaCare subsidies in case the administration loses in court.

“I think it has to be a federal fix,” Scott told reporters at the event he hosted Tuesday for GOP presidential candidates, according to The Washington Post.